In the past, it has been the practice in constructing glass melting furnaces, particularly of the regenerative type, to provide the brick regenerators which extend from below the floor of the glass plant to approximately the height, or slightly thereabove, of the melter itself. Each of the checkerworks or regenerators extends along the full length of the melter and is provided on the outside thereof with cleanout panels, usually having a panel associated with each of the firing ports. The cleanout panel associated with the first firing port closest to the charging end of the melter generally is provided in the end of the regenerator, while the other cleanout panels usually correspond to the firing ports with perhaps the last firing port having its cleanout panels in the opposite end wall of the furnace regenerative, checkerwork structure. As the melter is put in service, the products of combustion exhaust through the side ports and pass down through the checkerworks on the exhaust side, heating the checkerworks and the bricks which form the checkerworks will pick up the temperature of the exhaust air. On the reverse cycle of operation, the incoming air, which is used to support combustion within the melter, is passed upwardly through the previously heated checkerworks, and thus the air becomes preheated at the time that it is introduced into the melter, and the opposite side then becomes the exhaust side of the system. This cycling of the combustion and preheat air and the attendant exhaust of the products of combustion reverses and takes place in approximately thirty minute intervals. During this time, as can readily be seen, the checkerworks heat up and cool down to a certain degree in the cycle of operation of the side port regenerative furnaces. End port furnaces, which provide a firing system where the firing occurs through ports in the end of the furnace and exhaust is also through the end of the furnace, still have the same reversing operations. The checkerworks, however, are generally built at the firing end of the furnace.
In these operations, the heatup and cool down that occurs within the checkerworks normally results in a significant amount of expansion and contraction and thereby creates cracks and other possible air movement paths from the inside or outside of the checkerworks or regenerators into the atmosphere or interior thereof. This may occur as an infiltration of cool air into the hot checkerworks at a position on the exhaust side which is usually at a negative pressure or also can result in the preheated air escaping through the wall in areas where it is not desirable. In the area of the cleanout panels, it has been a fairly well known phenomenon that the outside air and the preheated air will move through the cleanout panels to a much greater extent than the areas which are much thicker in wall thickness. Further, the cleanout panels are formed of a plurality of holes alternating with larger thicknesses of brick, with the holes being the access ports through which air lances are used to clean the interior of the checkerworks and to blow down the collected dust particles to the lower cleanout canals. These holes are generally poorly plugged with tapered soft bricks and a great deal of leakage occurs at these locations.